// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * pwm-fan.c - Hwmon driver for fans connected to PWM lines.
 *
 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
 *
 * Author: Kamil Debski <k.debski@samsung.com>
 */

#include <linux/hwmon-sysfs.h>
#include <linux/hwmon.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/regulator/consumer.h>
#include <linux/sysfs.h>
#include <linux/thermal.h>
#include <linux/timer.h>

#define MAX_PWM 255

struct pwm_fan_ctx {
    struct mutex lock;
    struct pwm_device* pwm;
    struct regulator* reg_en;

    int irq;
    atomic_t pulses;
    unsigned int rpm;
    u8 pulses_per_revolution;
    ktime_t sample_start;
    struct timer_list rpm_timer;

    unsigned int pwm_value;
    unsigned int pwm_fan_state;
    unsigned int pwm_fan_max_state;
    unsigned int* pwm_fan_cooling_levels;
    struct thermal_cooling_device* cdev;
};

/* This handler assumes self resetting edge triggered interrupt. */
static irqreturn_t pulse_handler(int irq, void* dev_id)
{
    struct pwm_fan_ctx* ctx = dev_id;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    atomic_inc(&ctx->pulses);

    return IRQ_HANDLED;
}

static void sample_timer(struct timer_list* t)
{
    struct pwm_fan_ctx* ctx = from_timer(ctx, t, rpm_timer);
    unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
    int pulses;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    if (delta) {
        pulses = atomic_read(&ctx->pulses);
        atomic_sub(pulses, &ctx->pulses);
        ctx->rpm = (unsigned int)(pulses * 1000 * 60) / (ctx->pulses_per_revolution * delta);

        ctx->sample_start = ktime_get();
    }

    mod_timer(&ctx->rpm_timer, jiffies + HZ);
}

static int __set_pwm(struct pwm_fan_ctx* ctx, unsigned long pwm)
{
    unsigned long period;
    int ret = 0;
    struct pwm_state state = {};
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    mutex_lock(&ctx->lock);
    if (ctx->pwm_value == pwm)
        goto exit_set_pwm_err;

    pwm_init_state(ctx->pwm, &state);
    period = ctx->pwm->args.period;
    state.duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
    state.enabled = pwm ? true : false;

    ret = pwm_apply_state(ctx->pwm, &state);
    if (!ret)
        ctx->pwm_value = pwm;
exit_set_pwm_err:
    mutex_unlock(&ctx->lock);
    return ret;
}

static void pwm_fan_update_state(struct pwm_fan_ctx* ctx, unsigned long pwm)
{
    int i;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    for (i = 0; i < ctx->pwm_fan_max_state; ++i)
        if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
            break;

    ctx->pwm_fan_state = i;
}

static ssize_t pwm_store(struct device* dev, struct device_attribute* attr,
    const char* buf, size_t count)
{
    struct pwm_fan_ctx* ctx = dev_get_drvdata(dev);
    unsigned long pwm;
    int ret;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
        return -EINVAL;

    ret = __set_pwm(ctx, pwm);
    if (ret)
        return ret;

    pwm_fan_update_state(ctx, pwm);
    return count;
}

static ssize_t pwm_show(struct device* dev, struct device_attribute* attr,
    char* buf)
{
    struct pwm_fan_ctx* ctx = dev_get_drvdata(dev);
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return sprintf(buf, "%u\n", ctx->pwm_value);
}

static ssize_t rpm_show(struct device* dev,
    struct device_attribute* attr, char* buf)
{
    struct pwm_fan_ctx* ctx = dev_get_drvdata(dev);
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return sprintf(buf, "%u\n", ctx->rpm);
}

static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);

static struct attribute* pwm_fan_attrs[] = {
    &sensor_dev_attr_pwm1.dev_attr.attr,
    &sensor_dev_attr_fan1_input.dev_attr.attr,
    NULL,
};

static umode_t pwm_fan_attrs_visible(struct kobject* kobj, struct attribute* a,
    int n)
{
    struct device* dev = container_of(kobj, struct device, kobj);
    struct pwm_fan_ctx* ctx = dev_get_drvdata(dev);
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    /* Hide fan_input in case no interrupt is available  */
    if (n == 1 && ctx->irq <= 0)
        return 0;

    return a->mode;
}

static const struct attribute_group pwm_fan_group = {
    .attrs = pwm_fan_attrs,
    .is_visible = pwm_fan_attrs_visible,
};

static const struct attribute_group* pwm_fan_groups[] = {
    &pwm_fan_group,
    NULL,
};

/* thermal cooling device callbacks */
static int pwm_fan_get_max_state(struct thermal_cooling_device* cdev,
    unsigned long* state)
{
    struct pwm_fan_ctx* ctx = cdev->devdata;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    if (!ctx)
        return -EINVAL;

    *state = ctx->pwm_fan_max_state;

    return 0;
}

static int pwm_fan_get_cur_state(struct thermal_cooling_device* cdev,
    unsigned long* state)
{
    struct pwm_fan_ctx* ctx = cdev->devdata;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    if (!ctx)
        return -EINVAL;

    *state = ctx->pwm_fan_state;

    return 0;
}

static int
pwm_fan_set_cur_state(struct thermal_cooling_device* cdev, unsigned long state)
{
    struct pwm_fan_ctx* ctx = cdev->devdata;
    int ret;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    if (!ctx || (state > ctx->pwm_fan_max_state))
        return -EINVAL;

    if (state == ctx->pwm_fan_state)
        return 0;

    ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
    if (ret) {
        dev_err(&cdev->device, "Cannot set pwm!\n");
        return ret;
    }

    ctx->pwm_fan_state = state;

    return ret;
}

static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
    .get_max_state = pwm_fan_get_max_state,
    .get_cur_state = pwm_fan_get_cur_state,
    .set_cur_state = pwm_fan_set_cur_state,
};

static int pwm_fan_of_get_cooling_data(struct device* dev,
    struct pwm_fan_ctx* ctx)
{
    struct device_node* np = dev->of_node;
    int num, i, ret;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    if (!of_find_property(np, "cooling-levels", NULL))
        return 0;

    ret = of_property_count_u32_elems(np, "cooling-levels");
    if (ret <= 0) {
        dev_err(dev, "Wrong data!\n");
        return ret ?: -EINVAL;
    }

    num = ret;
    ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
        GFP_KERNEL);
    if (!ctx->pwm_fan_cooling_levels)
        return -ENOMEM;

    ret = of_property_read_u32_array(np, "cooling-levels",
        ctx->pwm_fan_cooling_levels, num);
    if (ret) {
        dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
        return ret;
    }

    for (i = 0; i < num; i++) {
        if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
            dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
                ctx->pwm_fan_cooling_levels[i], MAX_PWM);
            return -EINVAL;
        }
    }

    ctx->pwm_fan_max_state = num - 1;

    return 0;
}

static void pwm_fan_regulator_disable(void* data)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    regulator_disable(data);
}

static void pwm_fan_pwm_disable(void* __ctx)
{
    struct pwm_fan_ctx* ctx = __ctx;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    pwm_disable(ctx->pwm);
    del_timer_sync(&ctx->rpm_timer);
}

static int pwm_fan_probe(struct platform_device* pdev)
{

    struct thermal_cooling_device* cdev;
    struct device* dev = &pdev->dev;
    struct pwm_fan_ctx* ctx;
    struct device* hwmon;
    int ret;
    struct pwm_state state = {};
    u32 ppr = 2;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
    if (!ctx)
        return -ENOMEM;

    mutex_init(&ctx->lock);

    ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
    if (IS_ERR(ctx->pwm))
        return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");

    platform_set_drvdata(pdev, ctx);

    ctx->irq = platform_get_irq_optional(pdev, 0);
    if (ctx->irq == -EPROBE_DEFER)
        return ctx->irq;

    ctx->reg_en = devm_regulator_get_optional(dev, "fan");
    if (IS_ERR(ctx->reg_en)) {
        if (PTR_ERR(ctx->reg_en) != -ENODEV)
            return PTR_ERR(ctx->reg_en);

        ctx->reg_en = NULL;
    } else {
        ret = regulator_enable(ctx->reg_en);
        if (ret) {
            dev_err(dev, "Failed to enable fan supply: %d\n", ret);
            return ret;
        }
        ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
            ctx->reg_en);
        if (ret)
            return ret;
    }

    ctx->pwm_value = MAX_PWM;

    pwm_init_state(ctx->pwm, &state);
    /*
     * __set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
     * long. Check this here to prevent the fan running at a too low
     * frequency.
     */
    if (state.period > ULONG_MAX / MAX_PWM + 1) {
        dev_err(dev, "Configured period too big\n");
        return -EINVAL;
    }

    /* Set duty cycle to maximum allowed and enable PWM output */
    state.duty_cycle = ctx->pwm->args.period - 1;
    state.enabled = true;

    ret = pwm_apply_state(ctx->pwm, &state);
    if (ret) {
        dev_err(dev, "Failed to configure PWM: %d\n", ret);
        return ret;
    }
    timer_setup(&ctx->rpm_timer, sample_timer, 0);
    ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx);
    if (ret)
        return ret;

    of_property_read_u32(dev->of_node, "pulses-per-revolution", &ppr);
    ctx->pulses_per_revolution = ppr;
    if (!ctx->pulses_per_revolution) {
        dev_err(dev, "pulses-per-revolution can't be zero.\n");
        return -EINVAL;
    }

    if (ctx->irq > 0) {
        ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
            pdev->name, ctx);
        if (ret) {
            dev_err(dev, "Failed to request interrupt: %d\n", ret);
            return ret;
        }
        ctx->sample_start = ktime_get();
        mod_timer(&ctx->rpm_timer, jiffies + HZ);
    }

    hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
        ctx, pwm_fan_groups);
    if (IS_ERR(hwmon)) {
        dev_err(dev, "Failed to register hwmon device\n");
        return PTR_ERR(hwmon);
    }

    ret = pwm_fan_of_get_cooling_data(dev, ctx);
    if (ret)
        return ret;

    ctx->pwm_fan_state = ctx->pwm_fan_max_state;
    if (IS_ENABLED(CONFIG_THERMAL)) {
        cdev = devm_thermal_of_cooling_device_register(dev,
            dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
        if (IS_ERR(cdev)) {
            ret = PTR_ERR(cdev);
            dev_err(dev,
                "Failed to register pwm-fan as cooling device: %d\n",
                ret);
            return ret;
        }
        ctx->cdev = cdev;
        thermal_cdev_update(cdev);
    }

    return 0;
}

static int pwm_fan_disable(struct device* dev)
{
    struct pwm_fan_ctx* ctx = dev_get_drvdata(dev);
    struct pwm_args args;
    int ret;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    pwm_get_args(ctx->pwm, &args);

    if (ctx->pwm_value) {
        ret = pwm_config(ctx->pwm, 0, args.period);
        if (ret < 0)
            return ret;

        pwm_disable(ctx->pwm);
    }

    if (ctx->reg_en) {
        ret = regulator_disable(ctx->reg_en);
        if (ret) {
            dev_err(dev, "Failed to disable fan supply: %d\n", ret);
            return ret;
        }
    }

    return 0;
}

static void pwm_fan_shutdown(struct platform_device* pdev)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    pwm_fan_disable(&pdev->dev);
}

#ifdef CONFIG_PM_SLEEP
static int pwm_fan_suspend(struct device* dev)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return pwm_fan_disable(dev);
}

static int pwm_fan_resume(struct device* dev)
{

    struct pwm_fan_ctx* ctx = dev_get_drvdata(dev);
    struct pwm_args pargs;
    unsigned long duty;
    int ret;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    if (ctx->reg_en) {
        ret = regulator_enable(ctx->reg_en);
        if (ret) {
            dev_err(dev, "Failed to enable fan supply: %d\n", ret);
            return ret;
        }
    }

    if (ctx->pwm_value == 0)
        return 0;

    pwm_get_args(ctx->pwm, &pargs);
    duty = DIV_ROUND_UP_ULL(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
    ret = pwm_config(ctx->pwm, duty, pargs.period);
    if (ret)
        return ret;
    return pwm_enable(ctx->pwm);
}
#endif

static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);

static const struct of_device_id of_pwm_fan_match[] = {
    {
        .compatible = "hqyj,fan",
        //.compatible = "pwm-fan",
    },
    {},
};
MODULE_DEVICE_TABLE(of, of_pwm_fan_match);

static struct platform_driver pwm_fan_driver = {
    .probe = pwm_fan_probe,
    .shutdown = pwm_fan_shutdown,
    .driver = {
        .name = "pwm-fan",
        .pm = &pwm_fan_pm,
        .of_match_table = of_pwm_fan_match,
    },
};

module_platform_driver(pwm_fan_driver);

MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
MODULE_ALIAS("platform:pwm-fan");
MODULE_DESCRIPTION("PWM FAN driver");
MODULE_LICENSE("GPL");
